So with an interview in 4Gamer that got translated, it looks like their is four more planned DLC for the game, but it may not be finished until 2019 cause Tabata didn't want the quality to suffer due to a self-imposed time limit of a year.

The next episode will be Episode Ardyn, but there is hints Lunafreya may finally get an Episode dedicated to her. There were also hints that one episode may even jump off of the "alternate ending" from Episode Ignis. So expect more FFXV for the next two years.